Aluminum dipping enamel, and article coated therewith



United States Patent" AL DEPING ENAMEL, AND ARTICLE CGATED THEREWITH John P. Mayer, Cleveland, and'Miris D. Wright, Lake wood, Ohio, assignors to The Glidden Qompany, Cleve-' land, fihio, a corporationof (thin No Drawing. Application June25, 1954 Serial No. 439,466

12 Claims. (Cl. 106-290) This invention relates to an improvedalum'inum dip-. ping enamel as a novel composition of matter,'and=-to articles coated therewith.

Aluminum finishes have been used in the past formany purposes, and brushing and spray coatings. having. aluminum flake as the principal pigment are well known; Conventional aluminum finishes have been applied by dipping, but preferably in connectionwith articles whose shape was such'that flow could be uniformly controlled." When the shape of the dippedrarticle is such that the finish tends to accumulate, as in a recess, and then to: flow out over other areas where the finishihas already drained and started to set, thenthe-fiow of'theflaccu' mulated finish over 'theother area causes a'rea'dily apparent streak or blemish due to a differencein'iheleafing pattern or build up of 'the:aluminum;'- For thi'sreason, the coating of articles with aluminum finishes'by dipping has heretofore been unsatisfact'ory: Mueli effort has been expended in the pastin attempts-"to overcomethe difficulties'describedabove, but to' thebest of 'our knowledge such efforts'have been of limited 'su'ccess."-

Aluminum finishes are also recognized to smudge the fingers when handled. This is due to-the-fact that in-a leafing-type finish suchas these, 'the individual plates' or" flakes of aluminum float to the *surface of'the'co'ating andcarry little or no protecting binder. Consequently,"

when the dry finish is handled, partofthese""looselybound flakes are removed and appear on the fingers as" less of the shapeof the article being dipped, applyaf durable coating of uniform appearance and good smudge resistance.

Accordingly, the main object of thisinvention'is to larly adapted for application by dipping, but useful'also as a general protective'coating.

This and other objects will be apparent from the following description of the invention.

The problem of avoiding a streaked and blemished finish on articles dipped in aluminum coating compositions has been one of much interest and importance in certain segments of the coating art. Many expedients have been tried andmuch-ingenuity has been exercised in seeking an answer to the problem. Wehave now discovered; however, that the problem canbe solved successfully by employing a particular class of film-forming materials as the sole or principal film-forming material. We are presently unable to give the reason(s) why these '50 provide a novel aluminum coating composition pardon-- ice materials solve the-problem,"sowe'canonly explainthe invention in terms of the kinds and proportions of ma-' terials which provide thesolution'thereto.

The film-forming materials in our formulations are of the hydrocarbon dryingioilclass, and are ofthe polymeric C -C conjugated "diole fi'n homopolyme'r' and/or i CQ-C diolefin-styrene copolymer types which have been polymerizedinsolvent'in" the presence of sodium or other alkali metal as'the polymerization catalyst. Polymeric hydrocarbon 'dryingoils' whichwe' have found to be useful in the present invention are described in U. S. Patents 2,264,811, 2,559,947, 2,631,175, 2,636,910, 2,652,342, 2,669,526 and 2,672,425. Anyof these drying oils and mixtures thereof can be employed in the present invention, but'we prefer the butadiene-styrene oils of U. S. Patents 2,559,947 and 2,652,342 and we especially prefer the modified butadienestyrene drying oils of the latter patent. The oils corresponding to that patent are oily sodium copolymers having 'an intrinsic viscosity between about 0:15and 0.3 and are composed of the following ingredients in the combined state:

of this-class ofoilcontaining between about 10% and" 50% of styrene, whethermodified or not with maleic anhydride for the related anhydridesl' Wehave also discovered, however, that such oils as Well as those of U. S. Patents 2,650,209 and 2,631,175 can be mixed with other film-forming materials such as drying'oils, bodied glyceride oils, and/or epoxidized glyceride oils. Mix-- tures of hydrocarbon dryingoilswith epoxidized glyceride oils are described and claimed in the copening ap plicatibnof Tulk and Neuhaus, Serial-No. 589,854, filed June 7, 1956. Where used, the additives here mentioned preferably amount to about 5 by Weight on the total film-forming material in the'mixture. The use of 5% linseed oilin our butadiene styrene-maleic drying oil dipping enamel imparts improved stripping properties, a factor of importance in clipping practice.

The film-forming components of the present invention can be pigmented with aluminum pigment of the leafing type'in any desired amount. Preferably, however, the pigmentzbinder ratio is kept such that finished coatings havin'g the gloss of enamels are produced.

The total solids of our aluminum coatings can be varied considerably by employing volatile hydrocarbon solvent(s) of" the aliphatic, predominantly aromatic and/or fully aromatic types. Driers are not necessary, but can be added if desired, particularly when accelerated air-drying'is desired. When driers are used, they can be of "the peroxide type or metallic drier type. Cobalt octoate or naphthenate is especially efiective- The use .of certain driers is described and claimed in the copending application of Kiebler, Zierand Baumhart, Serial No. 377,242, filed August 28, 1953. The coatings of this invention can be eiiectivelycured bybakingeither with or Without driers. Baking temperatures of 250-400 F. are useful.

. 5 The following examples illustrate the principles of our invention.

Example 1 Bodied butadiene (79.5%)-styrene (l9.5%)-l% maleic anhydride copolymer hydrocarbon drying oil prepared in accordance with U. S. Patent 2,652,342 and having a total solids content of 60% in mineral spirits with U-V viscosity (Gardner) pts 1 ,3 Mineral spirits pts 75 Solvent naphtha (coal tar) pts. 2 Hydrogenated naphtha 1 pts. 7 4 Aluminum paste 2 lbs 1.5

1A commercial product of the Shell Company containing about 80% aromatics, 5% naphthenes, and 21.3% parathnes, and having a boiling range of 380 F. (inltral) t o 4i2 F. (50%) and an end point of 500 F., a specific gravity of .892 at 60/60 F., a closed cup flash point of 158 F. (Tag), a mixed aniline point of 84 F., and a Lauri butanol value of 73; commercially identified as E-407-R solvent.

A commercial product of the Reynolds Company and identified as N 0.47 aluminum paste. 7

The above materials were made into a coating composition by. mixing them together thoroughly. The finished composition had a weight per gallon of 7.81 lbs. and a viscosity (full body) of 19 seconds on a Zahn No. 2 viscosimeter. The coating was applied at full body to various articles by dipping, allowing a 12 minute drip time followed by an 11 minute bake at 350 F. The coated articles, even when of complex shape, exhibited excellent uniformity of appearance and excellent resistance to smudging.

Example 2 The coating of Example 1 was modified by. adding linseed oil thereto in an amount corresponding to 5% by weight on the butadiene-styrene-maleic copolymer drying oil. The modified coating retained its desirable appearance and non-smudging features but in addition The copolymer of Example 1 was replaced with a sodium-catalyzed unbodied homopolymer of butadiene of e the type prepared in accordance with U. S. Patent No.

2,631,175. The resulting coating, after being applied by dipping and cured by baking, exhibited a good uniform appearance free of streaking.

Example 4 vThe copolymer of Example 1 was replaced with an unbodied copolymer prepared from 50% butadiene and 50% styrene by a process conforming to that of U. S. Patent 2,636,910. The composition yields substantially the same good results obtained in Example 1.

Having now described our invention, what we claim is:

1. An improved aluminum dipping enamel composed essentially of: (A) an organic solvent solution of filmforming material composed essentially of alkali-metalcatalyzed, solvent-polymerized, hydrocarbon drying oil selected from the class consisting of C -C conjugated diolefin homopolymers, copolymers composed essentially of 50-90% C conjugated diolefins and 50-10% styrene, and mixtures thereof; and (B). leafing aluminum pigment dispersed in said vehicle in amounts at least sufiicient to provide hiding in an applied film thereof.

2. A coating composition as claimed in claim 1 .wherein the film-forming vehicle is composed essentially of a butadiene-styrene copolymer.

3. A coating composition as claimed in claim 2 wherein the butadiene-styrene copolymer is modified with Unless stripped periodically from the from .01 to 2.5% of an anhydride selected from the class consisting of maleic, chloromaleic and citraconic anhydrides.

4. A coating composition as claimed in claim 3 where in the said modifier is maleic anhydride.

5. A coating composition as claimed in claim 4 wherein said composition includes in the film-forming vehicle thereof up to about 5% triglycerides selected from the class consisting of drying oils, bodied triglyceride oils, epoxidized glyceride oils, and mixtures thereof.

6. A coating composition as claimed in claim 5 wherein said triglyceride oil is linseed oil 7. A coating composition as claimed in claim 1 wherein said composition includes in the film-forming vehicle thereof up to about 5% triglycerides selected from the class consisting of drying oils, bodied triglyceride oils, epoxidized glycerideoilsyand mixtures thereof.

3. A coating composition as claimed in claim 7 wherein said triglyceride oil is linseed oil. a

9. An article of manufacture having a surface portion thereof which when coated with liquid coating composition by dipping does not drainevenly, said surface having been coated with an aluminum p-igmented protective film by dipping said article in an enamel composition as claimed in claim 1 and then drying the retained composition, thereby providing on said article a coating having a uniform appearance free from blemishes customarily caused heretofore by uneven draining and flow of aluminum-pigmented wet coating material from the article.

10. An article of manufacture having a surface portion thereof which when coated with liquid coating composition by dipping does not drain evenly, said surface having been coated with an aluminum-pigmented protective film by dipping said article in an enamel composition as claimed in claim 6 and then drying the retained composition, thereby providing on said article a coating having a uniform appearance free from blemishes customarily caused heretofore by uneven draining and flow of aluminum-pigmented wet coating material from the article.

, 11. An article of manufacture having a surface portion thereof which when coated with liquid coating composition by dipping does not drain evenly, said surface having'been coated with an aluminum-pigmented protective film by dipping said article in an enamel composition as claimed in claim 7 and then drying the retained composition, thereby providing on said article a coating having a uniform appearance free from. blemishes customarily caused heretofore by uneven draining and flow of aluminum-pigmented wet coating material from the article.

12. An improved aluminum dipping enamel composed essentially of: (A) an organic solvent solution of filmforming material composed essentially of alkali-metalcatalyzed, solvent-polymerized hydrocarbon drying oil selected from the class consisting of C -C conjugated diolefin homopolymers, .copolymcrs composed essentially of 50-90% C -C conjugated diolefins and 50-10% styrene, and mixtures thereof; and (B) leafmg aluminum pigment dispersed in said vehicle in amounts at least sufiicient to provide hiding in an applied film thereof, said dipping enamel having a total solids content of about 22.6% by weight and having a ratio of copolymer solids to pigment solids of about 43.8.to 56.2.

References Cited in the file of this patent UNITED STATES PATENTS 2,441,945 Frolich et al. May 25, 1948 2,652,342 Gleason Sept. 15, 1953 2,662,027 Pike Dec. 8, 1953 2,669,526 Koenecke et a1. Feb. 16, 1954 

1. AN IMPROVED ALUMINUM DIPPING ENAMEL COMPOSED ESSENTIALLY OF: (A) AN ORGANIC SOLVENT SOLUTION OF FILMFORMING MATERIAL COMPOSED ESSENTIALLY OF ALKALI-METALCATALYZED, SOLVENT-POLYMERIZED, HYDROCARBON DRYING OIL SELECTED FROM THE CLASS CONSISTING OF C4-C8 COQUIGATED DIOLEFIN HOMOPOLYMERS, COPOLYMERS COMPOSED ESSENTIALLY OF 50-90% C4-C6 CONJUGATED DIOLEFINS AND 50-10% STYRENE, AND MIXTURES THEREOF; AND (B) LEAFING ALUMINUM PIGMENT DISPERSED IN SAID VEHICLE IN AMOUNTS AT LEAST SUFFICIENT TO PROVIDE HIDING IN AN APPLIED FILM THEREOF. 